Decided I wanna try to publish something, so I decided to start with something light.

As the title says, it's pretty much a collection of 42 great comets (comets big and bright enough to be visible to the unaided eye near perihelion) appeared in the last 2000 years, from Ceasar's comet of 44 BC to 1996's Hyakutake.

Some notes:

Since almost all of these comets passed before the advent of hi-tech telescopes, I assumed a diameter of 20 km for every one, with the following exceptions: Hyakutake (known to be 4.2 km across), fragments (which are sized as 20 km divided by the number of fragments of that comet), and the 1811 one (which was estimated to be around 35 km according to Wikipedia)

I set the "Epoch" to the perihelion passage date and "MeanAnomaly" to 0, so to find the perihelion passage date, simply bring up the comet's in-game wiki page and look at "Pericenter Epoch" in the "Orbit" page

Since luminosity also depends on random outbursts of activity, some of these comets are invisible from Earth even during perihelion. Usually they are a few magnitudes under 7 so increasing the minimum magnitude should reveal them.

For some reason comet tails don't seem to be rendered inside a sunlit atmosphere, so if you want to observe these comets as they appeared from Earth, I suggest to either look from orbit or disable atmospheres (as with the screenshot).

Just drop this file in the "\addons\catalogs\planets" folder and you should be ready to go comet-hunting in the past

Changelog:

February 26: First release, then removed non-alphanumerical characters from "de Cheseaux" (GC of 1744)

February 27: Added GC of 1887, GC of 1865, "Messier" (GC of 1769), and "Sarabat" (GC of 1729); renamed GC of 1881 to "Tebbutt" and GC of 1823 to "de Breaute-Pons"

There is a small mistake. Avoid to use non-alphanumerical characters in a catalog file (i.e. use only English letters). In my system with Russian as a default language language, I see this:

► Show Spoiler

SE displays correctly name of this comet in English localization and other localizations which uses win-1252 font. But in other localization it doesn't. To make a localized name of an object, use the SE wiki.

Source of the post However, can masses of comets be randomly generated, so that many of them do not have exactly the same size, but similar masses instead?

The problem is that even if I specify "Asteroid-class comet", without size and mass they become Gas giant-class planets in the game, for some reason.

And mass is even more random than size, given that the former is a function of not only the latter, but also of density, which can be anywhere from water-like (dirty snowballs) to silicate-like (icy dirtballs). So I just gave them a large-ish size.

But it could be nice if Asteroid-class objects (proper asteroids, comets, minor moons) were given a appropriate procedural mass and size without having to input either one.